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      <title>Kafka的事务机制 - 交互式测验</title>
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    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>Kafka的事务机制 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
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                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
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      <script>
        const quizData = [
  {
    "question": "根据文档，在 Kafka 生产者中启用事务机制，必须进行哪项关键配置？",
    "options": [
      "将 `acks` 设置为 `1`，以获得最快的响应速度。",
      "将 `retries` 设置为 `0`，以防止消息重复。",
      "指定一个唯一的 `transactional.id`，并确保 `acks` 设置为 `all`。",
      "启用 `enable.auto.commit` 以自动管理事务状态。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档明确指出，启用 Kafka 事务需要在生产者端进行两项核心配置：1. `transactional.id`：为事务生产者指定一个唯一的ID，用于在系统中标识该事务。2. `acks=all`：确保消息被所有同步副本确认，这是事务持久性和一致性的前提。",
    "source": "文档中「1. 事务的基本概念与配置」部分",
    "hint": "文档中的配置示例代码块展示了启用事务所需的两个必要参数。"
  },
  {
    "question": "在一个 Kafka 事务中，当生产者调用 `send()` 方法发送消息后，这些消息的直接状态是什么？",
    "options": [
      "消息被立即写入 Kafka 并对消费者可见。",
      "消息被标记为事务的一部分并先进行缓存，此时对消费者不可见。",
      "消息被发送到 Broker，但只有在主副本确认后才可见。",
      "消息会等待 `beginTransaction()` 方法被调用后才真正发送。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "在事务过程中，通过 `send()` 发送的消息并不会立即被持久化并对消费者可见。文档中提到，这些消息会被打上事务ID的标记，然后被缓存起来，直到整个事务被提交（commit）后，它们才会真正写入 Kafka 并变得可消费。",
    "source": "文档中「4. 发送事务消息」部分",
    "hint": "思考一下“全有全无”的原则，如果消息在发送后立即就可见，那么如何实现“全无”（回滚）呢？"
  },
  {
    "question": "Kafka 内部使用哪个特定的主题（Topic）来跟踪和存储所有事务的状态（如提交或回滚）？",
    "options": [
      "__consumer_offsets",
      "__transaction_state",
      "__transaction_log",
      "_kafka_internal_transactions"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档明确指出，Kafka 事务机制依赖于一个名为 `__transaction_state` 的内部主题来存储每个事务的状态信息，包括事务ID、事务状态（提交/回滚）等。这个主题是实现事务恢复和保证一致性的核心。",
    "source": "文档中「7. 事务消息的内部存储」部分",
    "hint": "Kafka 管理内部状态时，通常会使用带有双下划线前缀的特殊主题名称。"
  },
  {
    "question": "如果一个 Kafka 生产者在事务过程中遇到错误并调用了 `abortTransaction()` 方法，那么在这个事务中已经发送的消息会发生什么？",
    "options": [
      "这些消息会被提交，但会附带一个“已回滚”的标记。",
      "这些消息会被发送到一个特殊的死信队列（DLQ）。",
      "这些消息将被彻底丢弃，永远不会被持久化，消费者也无法读取到它们。",
      "这些消息会保留在 Broker 中，等待下一个事务来处理。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "调用 `abortTransaction()` 会触发事务回滚。根据文档描述，回滚操作会向 Kafka 发送回滚请求，更新事务日志状态，并且该事务内的所有消息都会被丢弃，不会写入 Kafka 分区，因此消费者永远无法访问到这些消息。",
    "source": "文档中「6. 回滚事务」部分",
    "hint": "回滚（Abort）操作的本质是撤销，这意味着事务内的所有操作都应该像从未发生过一样。"
  },
  {
    "question": "对于消费者而言，一个事务内的多条消息何时才变得可见和可消费？",
    "options": [
      "在生产者调用 `beginTransaction()` 之后。",
      "在所有消息都成功写入主副本（Leader）的日志后。",
      "在生产者成功执行 `commitTransaction()` 并且事务状态被最终确认后。",
      "只要消费者的隔离级别（isolation.level）设置为 `read_uncommitted` 就可以立即看到。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "这是 Kafka 事务的核心保证之一。文档在“提交事务”部分明确指出，只有当事务成功提交（`commitTransaction`）后，消费者才能读取到该事务中的消息。在此之前，即使消息已经发送到 Broker，它们对消费者也是不可见的（对于配置为 `read_committed` 的消费者而言）。",
    "source": "文档中「5. 提交事务」部分",
    "hint": "消费者的可见性与事务的最终状态直接相关。只有“已完成”的事务，其结果才是可信的。"
  },
  {
    "question": "根据文档，当一个启用了事务的 Kafka 生产者在事务过程中发生故障（例如崩溃），Kafka 会如何处理这个未完成的事务？",
    "options": [
      "Kafka 会无限期地等待该生产者重新连接来完成事务。",
      "Kafka 会自动删除所有来自该生产者的未提交消息，以清理资源。",
      "Kafka 会利用 `__transaction_state` 主题中的事务日志来恢复事务状态，并自动执行回滚或提交。",
      "Kafka 需要管理员手动介入，通过命令行工具来决定是提交还是回滚该事务。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档的“事务的失败与恢复”部分解释了 Kafka 的高可用性。系统不会依赖于故障的生产者或人工干预。相反，Kafka 会从 `__transaction_state` 主题中恢复事务的最后状态，并根据日志记录自动完成事务（回滚或提交），从而保证系统状态的一致性。",
    "source": "文档中「8. 事务的失败与恢复」部分",
    "hint": "一个健壮的分布式系统应该具备自动故障恢复的能力，而不是依赖于外部干预。"
  },
  {
    "question": "Kafka 事务机制最主要的目标是实现什么？",
    "options": [
      "提升生产者发送消息的整体吞吐量。",
      "确保生产者发送的一组消息要么全部成功可见，要么全部不成功，即“全有全无”的原子性。",
      "减少消费者处理消息时的重复率。",
      "降低生产者与 Kafka 集群之间的网络延迟。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档开篇就点明了 Kafka 引入事务机制的核心目的：“支持生产者端的消息原子性，确保消息的‘全有全无’语义”。这意味着可以将多条消息的发送操作捆绑成一个原子单元，这对于维护跨多个分区或主题的数据一致性至关重要。",
    "source": "文档开篇第一段",
    "hint": "文档的第一句话通常会阐明一个功能的核心目的。"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
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        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

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          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
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            li.dataset.index = index; // Store index in a data attribute
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            const currentQuestion = quizData[currentQuestionIndex];
            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
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            }, 0);

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            updateNavigationButtons();
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            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
            // 如果当前问题没有提示，则禁用提示按钮并隐藏提示内容
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                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
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                hintBtn.disabled = false;
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        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

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                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
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        function goToNextQuestion() {
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                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
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            } else {
                hintContainerEl.style.display = 'none';
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        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  